Influence of Seasonal Ground Water Level Fluctuations on the Stability of the Rohingya Refugee Camp Hills of Ukhiya, Teknaf, Cox’s Bazar, Bangladesh—A Threat for Sustainable Development

Bangladesh is a south Asian Monsoonal Country and the recent precipitation pattern in the Cox’s Bazar area of Bangladesh is changing and increasing the number of monsoonal slope failures and landslide hazards in the Kutubpalong & Balukhali Rohingya camp area. An attempt has been made to see the influence of seasonal variation of ground water level (G.W.L.) fluctuations on the stability of the eco hills and forests of Ukhiya Teknaf region. Ukhiya hills are in great danger because of cutting trees from the hill slopes and it is well established that due to recent change of climate, short term rainfall for few consecutive days during monsoon might show an influence on the factor of safety (Fs) values of the camp hill slopes. A clear G.W.L. variation between dry and wet seasons has an influence on the stability (Fs) values indicating that climate has a strong influence on the stability and threatening sustainable development. A stable or marginally stable slope might be unstable during raining and show a variation of ground water level (G.W.L.). The generation of pore water pressure (P.W.P.) is also influenced by seasonal variation of ground water level. During wet season negative P.W.P. called suction plays an important role to occur slope failures in the Ukhiya hills. Based on all calculated factor of safety values (Fs) at different locations, four (4) susceptible landslide risk zones are identified. They are very high risk (Fs = 0.18 to 0.46), high risk (Fs = 0.56 to 0.75), medium risk (Fs = 0.76 to 1.0) and marginally stable areas (Fs ≈ 1). Proper geo-engineering measures must be taken by the concerned authorizes to reduce P.W.P. during monsoon by installing rain water harvesting system, allowing sufficient drainage & other geotechnical measures to reduce the risk of slope failures in the Ukhiya hills. Based on the stability factor (Fs) at different slope locations of the camp hills, a risk map of the investigated area has been produced for the local community for their safety and to build up awareness & to motivate them to evacuate the site during monsoonal slope failures. The established “Risk Maps” can be used for future geological engineering works as well as for sustainable planning, design and construction purposes relating to adaptation and mitigation of landslide risks in the investigated area.

The Conservation of Ground Water Levels in the Peat Swamp Forest at Ayer Hitam North Forest Reserve, Muar in Johor, Malaysia

The management of peat swamp forests in Malaysia contends with two major issues: forest fires and the effects of abandoned forest-logging drainage systems or canals. Forest fire occurs during low rainfall season related to the local people activities. The drainage networks change the hydrological function of the intact forest ecosystem. A key function of the hydrological system in the undisturbed forest is to absorb water during rainfall season, thus delaying downstream runoff and preventing flash floods. The objective of the project described here is to restore the hydrological function of peat swamp forest (PSF) at Ayer Hitam North Forest Reserve (AHNFR) in Muar, Johor, Malaysia. The oil palm plantations, especially in the southern part of the area affect the forest reserve. Water flows out of the forest reserve through the drainage system constructed for managing these plantations. In 2016 and 2017, two water block structures or check dams were constructed near the boundaries of the forest reserve to hold the water and raise the groundwater level in the forest reserve. The implementation of the check dams at the two locations has conserved the groundwater level and subsequently, about 1.2 million m3 of water was saved annually from leaving the forest reserve from each of the check dam. This project is also part of the Coca-Cola Company’s sustainability commitment for water strategy with the global that is to replenish 100% of the equivalent volume of water consumed in their products and production by 2020. Replenishment is the key sustainability commitment for the Company.

Prediction of Ground Water Level in Arid Environment Using a Non-Deterministic Model

Modeling and forecasting of the groundwater water table are a major component of effective planning and management of water resources. One way to predict the groundwater level is analysis using a non-deterministic model. This study assessed the performance of such models in predicting the groundwater level at Kashan aquifer. Data from 36 piezometer wells in Kashan aquifer for 1999 to 2010 were used. The desired statistical interval was divided into two parts and statistics for 1990 to 2004 were used for modeling and statistics from 2005 to 2010 were used for valediction of the model. The Akaike criterion and correlation coefficients were used to determine the accuracy of the prediction models. The results indicated that the AR(2) model more accurately predicted ground water level in the plains;using this model, the groundwater water table was predicted for up to 60 mo.

Agrochemical Concentration Level in Zaria Dam Reservoir and Ground Waters in the Environs

This study examines the effect of agrochemical used for faming in the Galma Dam area on the quality of water in the reservoir and well water around the reservoir. Nine sampling points upstream of the Galma Dam were randomly se- lected for the study. Also, six hand dug wells in use by adjacent communities were identified for ground water samples. The study covered the period July to September 2011. All measurements were in accordance with the Standard Methods for the Examination of Water and Wastewater. The parameters measured and their mean concentrations from the reser- voir are in the order of: Chlorides (0.600 - 0.900 mg/l);Nitrates (0.009 - 0.019 mg/l);Bicarbonates;0.444 - 1.900 mg/l);Total Phosphates (0.173 - 3.077 mg/l);Sulphates (0.617 - 3.587 mg/l);and pH (6.4 - 7.5). For the well water samples, the results ranged from 1.58 - 3.10 mg/l;0.14 - 0.03 mg/l;0.60 - 2.73 mg/l;0.08 - 1.89 mg/l;0.33 - 2.66 mg/l and 6.05 - 7.0 respectively in the order previously listed. The results were statistically analyzed using ANOVA at 95% confidence level. Chlorides showed no significant variation between sampling points but significant variation with dates of sam- pling for surface and well waters. Nitrates variations with both sampling points and dates of sampling were insignificant. Bicarbonates variations with sampling points and dates of sampling were highly significant. Total Phosphates and Sul- phates variations with sampling points and dates of sampling were insignificant and significant respectively. pH values variations with sampling points and dates of sampling were insignificant and highly significant respectively. Generally, the mean concentrations are within the WHO maximum limits of the parameters in drinking water and recommenda- tions were made regarding the use of agrochemicals for farming in the area.

Use of Geosynthetic Access Mats in Construction

A stable surface to move manpower and equipment is a key for the construction operations. To create a stable road surface, the road construction techniques are time-consuming and expensive for a traditional construction which requires compaction of soil, aggregate base, sub-base and asphaltic layers. A Geosynthetic Access Mat (GAM) system can serve as an alternative to other traditional construction techniques to accommodate temporary construction. Due to its rigidity, the mat system can provide substantial vertical resistance to the applied load under a large deflection subject to soil conditions. This paper provides details of GAM specifications, soil conditions, applications, installation procedure, comparison with other soil stabilization methods and Aramco experience for deployments of these mats.

高水位软土公路路基土石方填筑施工技术研究

由于土石方填筑施工缺乏与实际工况的结合,导致存在高水位软土公路填筑路基沉降值超标的情况,为此,文中对高水位软土公路路基土石方填筑施工技术进行研究。收集高水位软土公路路基各土层的厚度、力学参数(压缩模量、抗剪强度等)等基本地质信息,结合水位分布以及高度,确定其对地基沉降情况的影响,计算高水位软土公路路基沉降状态。在土石方填筑施工阶段,结合计算结果,针对不同土层的具体情况,从填筑松铺厚度、填料粒径、碾压速度、碾压次数,以及特殊工况的施工基础进行针对性设计。应用路基填筑技术后,60 d的最大沉降值仅为0.66 mm,在沉降值允许范围(≤1.0 mm)内,且在50 d后,沉降逐渐收敛,10 d内,沉降值变化幅度仅为0.03 mm。

Effects of mining－induced earthquakes on water table in deep wells

Based on the systematical collection and processing of data on the influence of mining-induced earthquakes on water table regime in deep well Lu-15 in Taozhuang Coal Mine since 1980, we study the characteristics of coseismic effect of water table in deep well in this paper. We have found precursory phenomena of water table in deep well before mining-induced earthquake. Here we discuss the physical mechanism of coseismic effect of mining--induced earthquake on water table in deep well.

地下水位线倾斜的地面塌陷演化过程试验研究

为探究地下水位线倾斜情况下岩溶地面塌陷的演化过程,设计一种模拟地下水位倾斜致塌的试验装置。首先,以砂土为试验材料,考虑地下水位线倾斜角度及岩溶水位高度变化等因素,开展室内物理模型试验。其次,通过监测试验过程中孔隙水压力、竖向土压力、地表沉降量及岩溶通道渗流总量等数据,测绘塌陷体的空间形态,分析地面塌陷的演化过程。试验结果表明:距离岩溶通道孔口越近,土中的孔隙水压力降幅及水力梯度越大,加速了孔口附近土体的变形和破坏。岩溶水位下降会在土体内部形成降落漏斗,引起地下水渗流量的非线性增长。以临界土洞为界,岩溶地面塌陷可分为内部塌陷和地表塌陷2个阶段。随着地下水位线倾角的增大,岩溶通道的渗流强度减弱,土体内部偏压特征逐渐显著,且偏压条件会增强对土拱效应的削弱作用。塌陷体中心线向高水位侧的偏斜角度与地下水位线倾角呈正相关,其空间形态由漏斗状转为牛角状。最后,参考渗水条件下深埋隧道松动土压力的计算方法,对渗流作用下岩溶土洞顶部松动土压力进行求解,所得结果与实际试验数值较为吻合,具有一定的合理性和参考意义。

建筑工程深基坑施工中的地下水位监测技术

以佛山市某高层建筑施工项目作为研究案例,对地下水位监测技术进行深入研究,主要介绍了地下水位监测的目的、内容和方法,论述地下水监测点的布置要点,并对监测到的数据进行分析、评价。监测结果表明:该工程在施工过程中地下水的水位变化比较稳定,基坑始终处于安全状态,确保了项目如期顺利竣工。

地下水水位上升对隧道结构工程的影响研究——以北京某地铁地下线路为例

随着我国经济的迅速发展,使得城市轨道交通在城市中的地位越来越突出。地铁的开通,能有效解决交通拥堵、空气污染、土地资源短缺等问题。在地铁发展中,由于城市建设所带来的环境状况的变化,无论是新建还是现有的地铁,都会因地下水位的变动而受到影响。文章通过一个地铁工程实例,运用渗透模块模型,对地下水位升高对隧道结构的影响进行了简单的探讨。

榆次区地下水水位管控目标分析

榆次区属于地下水超采区,已暂停新增地下水取水许可,为早日实现地下水水位回升,解除地下水超载区限制,提出了超载区治理期间地下水水位管控目标,为水资源管理提供定量依据。

高潜水位采煤沉陷区人居环境与生态重构关键技术:以安徽淮北绿金湖为例

以两淮高潜水位矿区为代表的我国东部大量采煤沉陷积水区的形成,严重影响了煤炭资源型城市的可持续发展,特别是城中采煤沉陷区水土资源撂荒、生态系统紊乱、人居环境恶化已成为制约城市建设的三大瓶颈,严重阻碍了经济社会发展和生态文明建设。为解决煤炭资源型城市生态修复与可持续发展问题,通过分析高潜水位采煤沉陷区地表沉陷积水演化规律和生态损害特征,基于开采沉陷原理和“采复一体化”理论,提出了地表沉陷积水动态预测方法,构建了沉陷区地形改造分区重构数学模型;研发了沉陷区边采边复施工、水循环与水资源调控、建筑分区设计、水土流失控制与基质改良、水陆复合生态系统重构等关键技术;探索了城中采煤沉陷区人居环境与生态一体化治理新模式,并以淮北绿金湖沉陷区为工程背景,开展了工程实践。研究表明:①融合Knothe时间函数和水量平衡模型参数,可实现开采任意时刻地表沉陷积水深度、积水面积、积水体积和最大库容的精准预测,最大相对误差为9.7%;②依据土方量平衡条件,建立了采前地形重构数学模型,将沉陷治理区划分为以地表沉陷盆地中央为中心、两侧对称的中央挖深、边界垫浅4个特征区域,土地闲置时间由14个月缩短至8个月,为高潜水位采煤沉陷区“挖深垫浅”超前治理提供了理论依据;③研发了环保疏浚退水及人工湿地尾水处理系统、底泥一体化机械深度干化系统、高填筑围埝多级装配式退水系统等成套施工关键技术,退水效率提高了17%,节约排泥场面积5260 m^(2);④提出了“平整地建筑-斜坡地水土保持-浅水区水生植被-深水区生态渔业”沉陷区分区治理技术,实现了沉陷区水土资源的100%高效利用;⑤与引江济淮、生态走廊、绿金城市等重大民生工程相结合,探索了集市场运作、科学修复、可持续运营于一体的沉陷区综合治理新模式,为城中采煤沉陷区生态环境治理和可持续发展提供了理论依据和技术参考。

西部干旱区生态需水的规律及特点——以塔里木河下游绿色走廊为例

天然植被蒸散耗水量小 ,水分有效利用程度高 ,生态需水可塑性及水质变幅较大等是生态需水的主要特点 .保护塔里木河下游绿色走廊的生态需水量 ,主要是指大西海子以下自然植被的需水量 .即地下水位恢复总水量和全河段生态总维持水量 ,前者主要包括水位恢复水量、侧向排泄量及河道蒸发水量 .2 0 0 5年泄水目标为阿尔干 ,生态总需水量为恢复大西海子至阿尔干地下水的总水量 ,该水量为 13.2 0×10 8m3,年均需水量为 2 .6 4× 10 8m3.2 0 10年泄水目标及植被保护目标都是台特玛湖 ,生态总需水量包括恢复阿尔干至台特玛湖段地下水位的水量以及维持大西海子至台特玛湖段生态的维持水量 ,该水量为 18.32× 10 8m3,年均需水量为 3 .6 6× 10 8m3.2 0 10～ 2 0 30年的生态总需水量包括每年维持大西海子至台特玛湖段生态的总维持水量 ,同时也包括增加植被 18.6 7× 10 4 hm2 所需要的水量 ,2 0年生态总需水量为 139.0 0× 10 8m3,年均需水量为 6 .95× 10 8m3.通过一系列措施保证生态用水 ,是干旱区生态建设的关键 .

基于进化支持向量机的滑坡地下水位动态预测

地下水位动态预测对滑坡稳定性评价具有关键作用。滑坡地下水位演化过程是一个受水文地质条件控制,并受降雨、库水和气温等多种影响因素综合作用而发展演化的非线性动力系统,地下水位与其影响因素之间存在非线性响应关系。以三峡库区白家包滑坡地下水位监测数据为例,在深入分析滑坡地下水位变化特征及其与影响因素响应关系的基础上,利用非线性智能遗传算法和支持向量机建立进化支持向量机耦合模型,并对地下水位进行预测,其预测结果的均方差和相关系数的平方分别为0.013和0.929,说明预测结果与实测值较吻合。选择神经网络模型进行对比,耦合模型的均方差小154%,而相关系数的平方大10%。综合表明进化支持向量机耦合模型具有较好的拟合和泛化能力,是一种行之有效的滑坡地下水位预测方法。

毛乌素沙地不同水分梯度根系垂直分布与土壤水分关系的研究

通过对毛乌素沙地不同水分梯度根系垂直分布的研究表明:不同水分梯度根系分布随土壤深度的增加呈指数形式下降,不同梯度由于土壤水分、植被根系类型的差异,不同水分梯度植被根系的空间分布也有差异,不同梯度根量随土壤垂直深度的模拟方程分别为:y=9.5736e-0.1341x,R2=0.8859(I);y=16.246e-0.2037x,R2=0.9301(II);y=32.001e-0.1904x,R2=0.9544(III);y=28.336e-0.1993x,R2=0.9484(IV)。不同水分梯度土壤含水率变化程度不同,同一水分梯度各层土壤含水率变化幅度亦有差异,0.1m土壤含水率变异系数最大,随着土壤深度增加变异系数减小,根据土壤含水率变异系数分析我们将各层土壤水分垂直变化划分为活跃层(0-0.1m)、次活跃层(0.2-0.6m)、相对稳定层(1m)(I、II、III);而对IV梯度划为活跃层(0-0.1m、1m)、相对稳定层(0.3m)。根系生物量垂直分布与其对应土壤含水率有明显相反的关系,土壤含水率的变化与根系生物量的变化趋于相反,当土壤含水率增大时相应区域根系生物量减小;反之则增加。随水分梯度的增加各梯度最高水分利用层逐渐向表层发展,从第I梯度0.4m的6.84到第IV梯度0.1m的14.33。

塔里木河下游生态输水对植被和地下水位的影响

由于近 5 0a来人类不合理的资源开发 ,造成塔里木河下游的生态环境问题日趋严峻 .为拯救下游绿色走廊和改善下游环境 ,于 2 0 0 0年 7月始 ,实施了塔里木河下游应急生态输水工程 ,水流到达台特玛湖 .本文根据 2a来在塔里木河下游的监测结果 ,通过对下游天然植被的一些生态指标的变化和输水后地下水位变化等资料进行对比分析 ,发现随着输水工程的进行 ,距输水河道一定范围内地下水位升高明显 .相应地 ,下游植被的生态响应也很显著 ,沿河岸许多种草本植被又重新出现 ,而一些耐旱乔、灌木随着生境的改变 ,长势也出现明显好转 ,主要表现在植被盖度、植物多样性指数和丰富度指数的提高以及胡杨冠幅的加大 .同时 ,研究结果表明 ,截止 2 0 0 2年 9月 ,在塔里木河下游中段 ,生态输水对地下水影响范围为 80 0m ,天然植被恢复的范围为 70 0m .由于环境条件的差异 ,在不同区段的影响范围不一样 。

基于水分运移的若尔盖湿地SPAC模型研究

为正确评价与合理利用若尔盖湿地水资源,对湿地SPAC系统的水分运移规律进行研究。在分别研究土壤-植物-大气各子系统及其界面的基础上,输入模型计算所需参数数据,建立湿地SPAC耦合模型。采用实测的参数验证模型,并取一定幅度变动主要参数来运算,判别模型对不同参数的敏感性。结果表明,耦合模型可以较好地描述湿地的生态-水文过程,并得到湿地植物生长的“理想”的地下水埋深（60-100 cm）和“适宜”的地下水埋深（0-60 cm和100-250 cm）。

生态输水后塔里木河下游合理水位探讨

塔里木河下游应急生态输水工程改善了该区水资源匮乏的现状,地下水的平均水位从输水前的8.25m升至输水后的4.13m。相应地,地表植被也出现明显的响应。但是,在不同河段由于过水时间、耗水量等因素的差异,造成输水后水位差异较大。以既能减少地下水强烈蒸发返盐,又不造成土壤干旱而影响植物生长的合理生态水位作为评价标准,对输水后不同河段的地下水位进行分析。结果显示,目前英苏—阿拉干段的地下水位2.97～4.8m是比较理想的水位;大西海子—英苏段水位较高,可能出现次生盐渍化;阿拉干—台特玛湖段地下水位太低,不利于植被的自然恢复。

红壤性水稻土Eh动态变化及其影响因素初探

通过田间原位测定长期定位试验20cm和80cm地下水位下3种施肥处理水稻土氧化还原电位值(Eh值),阐明已培肥红壤性水稻土晚稻生长期间Eh的动态变化,并初步探讨影响水稻土Eh变化的主要因素。研究结果表明,在晚稻生育期间,各处理Eh变化趋势一致,基本上在水稻生长返青期处于最低水平,分蘖初期和分蘖盛期、拔节抽穗期、扬花期和灌浆期处于较低水平且变幅较小,至烤田期排水落干,Eh出现明显增幅;其中,在淹水期和烤田期,供试土壤Eh平均值分别在-144.79^-107.05mV和140.27~372.60mV之间。方差分析结果表明,观测时期(组内效应)对Eh变化有显著意义,表明影响水稻土Eh的众因素变化较大,在不同时期对Eh的综合影响显著不同。水分是决定Eh变化的关键因素,土壤水分与水稻土Eh有极显著的负相关性(r=-0.364^(**),n=126),且水位对水稻土Eh变化影响显著(p<0.05),水位越低,Eh越高,低水位处理Eh值平均高出高水位处理Eb值37.4%左右,且水位对水稻土Eh的影响较稳定。施肥对整个生育期Eh变化也有显著影响(p<0.05),但施肥对Eh的影响不稳定,仅在返青期、分蘖初期和烤田期对Eh变化起显著作用,有机肥能降低返青期至分蘖初期水稻土Eh。高、低水位下3种施肥处理在晚稻不同生育期近根点Eh均值均大于远根点,表明水稻根系能小幅提高水稻土Eh值。此外,Eh变化与5cm处土温显著相关,而土壤有机碳对Eh变化的影响因被有机肥掩盖,二者之间相关性不显著。